An environmentally conscious remediation process for the emergency treatment/disposal of hydrazine fuels spills is needed. The highly toxic hydrazine family of fuels is utilized as rocket propellants in virtually all U.S. space programs including both launch vehicles and satellite propulsion systems. Since large volumes of these fuels are annually shipped all over the United States, accidental major spills of these propellants could potentially occur near populated communities during transport over the nation's highways. In addition, smaller spills could also occur during launch operations and storage at the user facilities.
An inadvertent release of hydrazine to the environment can be extremely hazardous due to the mutagenic nature of such chemical compounds, which can induce tumor growth in human beings years following even a low level exposure. Hydrazine compounds are classified as suspected human carcinogens and their permissible levels of exposure have been reduced to 10 parts per billion (ppb). A hydrazine spill remediation process, to be developed, should not only destroy the propellant fuel but also should not generate other hazardous materials. An in-situ processing method involving direct application of the treatment reagent or process to the spill is preferred.
Currently, a small hydrazine spill, occurring at launch facilities, is washed down with water. The diluted water is treated with an oxidizing agent such as sodium hypochlorite or alternatively, the hydrazine containing water is transported to a hazardous waste facility for incineration. The former treatment method with UDMH is unsatisfactory in that a strong carcinogen, n-Nitrosodimethylamine, is generated. In addition, the hypochlorite oxidation of both UDMH and MMH yields volatile halogenated hydrocarbons, which are priority pollutants. In the case of a spill on soil, the contaminated material is transported for disposal at an incineration facility.
An accident involving a transport trailer may spill four to five thousand gallons of the hydrazine fuel, whereas a catastrophic failure of a fuel storage vessel at a launch facility may release twenty thousand gallons or more of the propellant. A rail car derailment resulting in a hydrazine (i.e., commercial use) release occurred in Southern California several years ago.
A major spill of a hydrazine transport trailer could potentially result in legal action amounting to millions of dollars. Additionally, minor hydrazine spills resulting from leaks or other causes are not unusual during space launch operations. These spills, which can result in evacuations and expensive launch delays, are washed down into the waste fuel tank for later disposal. A greater concern is a major accidental spill of a hydrazine transport trailer, occurring off-site during shipment of the propellant over the public highways. Although such an incident has not occurred to date, a treatment/disposal process should be developed and be available when needed. An environmentally conscious, inexpensive method for the complete conversion of the spilled hydrazine into innocuous materials is needed. This treatment process may entail chemical reactions, bioremediation, or other methods such as pyrolysis, photolysis, or catalysis.
Hydrazine group compounds, including hydrazine, monomethylhdrazine (MMH), and 1,1-dimethylhydrazine (UDMH), are widely used as fuels (e.g., in rocket propulsion systems and fighter jets), corrosion inhibitors (e.g., nuclear industry), catalysts, emulsifiers, or dyes. Hydrazine is typically utilized as a monopropellant in rocket propulsion applications because it can readily ignite when placed in contact with noble metal catalysts. Hydrazine is particularly popular with satellite companies because hydrazine, when used as a monopropellant, saves space, complexity and weight. Hydrazine and hydrazine-based compounds can also function as a precursors in the synthesis of a number of drugs, polymers, plasticizers and pesticides. As indicated above, however, hydrazine is also extremely toxic and dangerous. Note that as utilized herein, the term “hydrazine” is generally analogous to the chemical formula N2H4, while the term monomethylhdrazine (MMH) is generally analogous to the chemical formula CH3NHNH2.) Additionally, the term dimethylhydrazine (UDMH) can be referred to by the chemical formula (CH3)2NNH2.
The U.S. Occupational Safety and Health Administration (OSHA), for example, requires the prevention of exposure to hydrazine and its derivatives at concentrations greater than one part per million (1.3 mg/m3). Hydrazine and hydrazine derivatives are readily combustible reducing agents that react violently with oxidizing agents and thus present a serious safety hazard. Hydrazine and hydrazine derivatives are well known components of liquid rocket fuels in conjunction with an oxidizing agent such as dinitrogen tetroxide. Thus, at facilities where liquid-fueled rockets are prepared for flight, there is a particular need to provide reliable and sensitive methods and systems for decontaminating objects, such as fighter jets and maintenance equipment thereof, and exposed environments which can become contaminated with hydrazine. Ideally, such hydrazine remediation methods and systems should also have a limited, if negligible effect on the environment.
Many reactions of hydrazine with dicarbonyl compounds are known. For example, Gerd Kaupp and Jens Schmeyers have investigated hydrazine reactivity, as reported in “Solid-State Reactivity of the Hydrazine-Hydroquinone Complex,” J. Phys. Org. Chem 2000, 13: pp. 388–394, which is incorporated herein by reference. Kaupp and Schmeyers investigated the solid-state reactivities of the hydrazine-hydroquinone 1:1 complex and of hydrazine hydrochloride with solid aldehydes, ketones, carboxylic acids, thiohydantoin and 4-nitrophenyl isothiocyanate. Kaupp and Schmeyers reported that only the hydrazine complex provides quantitative additions, condensations, ring openings and ring closures. The solid-state mechanisms were investigated by atomic force microscopy (AFM) and far-reaching anisotropic molecular movements were correlated with the crystal packing, both on the hydrazine complex surface and on the surface of two benzaldehydes. Based on this research Kaupp and Schmeyers concluded that the hydrazine can move into the aldehyde crystals for chemical reaction without melting. Kaupp and Schmeyers also reported that characteristic surface features could be created by common phase rebuilding and phase transformation on both the hydrazine-donating and -accepting crystals.
The present inventors have examined compounds that will react with hydrazine rapidly and quantitatively. The present inventors have investigated several compound classes in order to tailor these derivatives of hydrazine for facile detection (i.e., to required levels) by current analytical methods.
Decontamination methods and systems can be separated into three major categories: physical removal, chemical inactivation, or a combination of both physical and chemical means. Wiping, sweeping, scraping, blowing, vacuuming, rinsing with water, and steam cleaning are all examples of physical methods for the removal of contaminants. In many cases, physical removal of gross contamination is an initial step in decontamination and remediation thereof. Physical removal of gross contamination usually is not sufficient to reduce contaminant concentrations to background levels. In most cases, physical removal is followed by a wash and rinse process using cleaning solutions. These cleaning solutions often dissolve contaminants and keep them in a solution until they can be rinsed away. Rinsing removes contaminants from an affected object or area through the dual process of dilution and solubilization. Multiple rinses with clean water can remove more contaminants than a single rinse.
Despite use of present cleaning solutions and rinsing procedures, contaminants generally still persist after remediation, although in a diluted form, and can be relocated to areas surrounding the object or area targeted for decontamination. Such is the case where hydrazine is diluted and allowed to run off along a surface (e.g., earth or pavement) away from the decontamination zone, or worse is absorbed into the earth and into water aquifers.
More effective methods and systems are needed for remediating hydrazine from contaminated objects, solutions, and areas. The present inventors recognize this need and have invented method of and systems for hydrazine remediation.